IL6 and neoplasm: Tumor ECs produce several angiocrine factors, such as vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), interlukin-6 (IL-6), interlukin-8 (IL-8), transforming growth factor beta (TGF-β), platelet-derived growth factor-beta (PDGF-β), that foster angiogenesis and immune suppression leading to chemoresistance [35,36,37].